1. Field of Endeavor
The present invention relates to medical devices and processes used in bone fixation, and more specifically to bone screws.
2. Brief Description of the Related Art
Bone screws, including pedicle screws, have been used for years to provide an anchor into bone in order to secure other devices to the bone. While advances have been made in such bone screws, current designs do not accommodate all uses and anatomy. For example, U.S. Pat. No. 5,207,678, issued to Harms et al., describes a bone screw assembly that requires the bone screw itself to be assembled with other parts of the device prior to driving the bone screw into bone. While this configuration has been quite popular, in some circumstances it can be desirable to position the bone screw itself in the desired location in bone, and thereafter assemble the remaining elements of the bone screw assembly. Because the bone screw assembly described in the '678 patent includes a top-mounted screw, that is, one in which the bone screw 2 must be inserted through the top of its housing 6 before driving the screw 2 into bone, the practitioner must drive the bone screw with the housing 6 loosely attached to the proximal end of the screw, thus potentially interfering with driving the screw and obstructing the practitioner's view of the screw head and the bone insertion point.
There remains a need for bone screws which can be used to anchor other devices to bone which address, and even overcome, some or all of the deficiencies in the prior art devices.